1. Field of the Invention
The present invention relates to a data holding circuit, and in particular, to a data holding circuit that reduces a setup-hold time when data is inputted.
2. Background of the Related Art
FIG. 1 illustrates a related art data holding circuit, and FIGS. 2A-2C illustrate waveforms of signals of each element of the circuit of FIG. 1. As shown in FIG. 1, the related art data holding circuit includes a three-phase buffer TB into which input data ID is inputted. The three-phase buffer TB is enabled in accordance with a control signal IMCLK to output an output data OD.
The operation of the related art data holding circuit will now be described. When input data ID is inputted into three-phase buffer TB and then the control signal IMCLK is transited to a high level, the three-phase buffer TB is enabled to output the output data OD.
As shown in FIG. 2B, the input data ID should be inputted and setup before the control signal IMCLK is transited to a high level. The inputted data ID should also be held long enough after the three phase buffer TB is enabled to effectively output the output data OD, which is shown in FIG. 2C.
Therefore, the control signal IMCLK must setup early enough before the control signal IMCLK is transited to a high level for the input data ID to be effectively outputted as the output data OD. Similarly, after the control signal IMCLK is transited, the input data ID must be held, which disadvantageously extends the setup time and hold time.
In addition, when the output data OD is outputted via a data bus, the loading of the output data OD is large. Thus, a rising time until the output data OD transitions to a high level and a falling time until the output data OD transitions to a low level can be extended. Accordingly, an extended setup time and an extended hold time are needed to effectively obtain the output data OD using a data bus.
The above references are incorporated by reference herein where appropriate for appropriate teachings of additional or alternative details, features and/or technical background.